| At present,with the increasingly severe energy shortage and environmental pollution,traditional automobiles are facing tremendous pressure in energy conservation and emission reduction,therefore improving vehicle thermal management and aerodynamic performance is undoubtedly one of the important ways to solve such problems.However,according to the previous research results,the current research on vehicle thermal management mostly analyzes the air flow and heat transfer characteristics in the cabin from a macro perspective,but ignores the coupling relationship between the condenser and the radiator.The performance of the engine cooling system and the air conditioning system is also analyzed independently.In addition,in order to solve the problem of heat dissipation inside the cabin,increasing the grille opening area is usually used to increase the intake flow of the heat exchanger,but this will undoubtedly increase the internal flow resistance,thus affecting the vehicle’s aerodynamic performance.Therefore,how to comprehensively analyze and improve the thermal management and aerodynamic performance of vehicles is particularly important.In this paper,a 1D and 3D coupling simulation method is used to comprehensively analyze the thermal management and aerodynamic performance of a traditional fuel vehicle.Firstly,1D and 3D simulation models are built based on Amesim and STAR-CCM+software respectively,and the heat exchanger modules（condenser,radiator and intercooler）are used as the bridge to realize the data transfer between the one-dimensional and three-dimensional simulations.The accuracy of the simulation method is verified according to the heat balance test of the environmental cabin.Secondly,by analyzing the 1D/3D simulation results of the vehicle at idle speed,low-speed climbing and high-speed operating conditions,the problems existing in different operating conditions are determined:at the condition of idle speed,the cooling capacity of the evaporator is low due to the low refrigerant flow rate of the air-conditioning system,and the overall temperature inside the cabin is high,which affects the heat exchange capacity of the condenser,so the air-conditioning system has the worst refrigeration performance under this operating condition.Under the condition of low-speed climbing,the engine cooling system has the worst heat dissipation performance and the engine outlet coolant temperature is too high due to the low intake air flow of radiator and high engine heat load,so the allowable ambient temperature has not met the design requirements.The wind resistance coefficient of the vehicle at high speed is 0.3761.By analyzing the aerodynamic performance in the cabin under this operating condition,it is found that the internal flow resistance of this vehicle accounts for 12.31%of the aerodynamic resistance,which is much higher than the average level of similar vehicles.Finally,aiming at the existing problems of the vehicle,the performance of the vehicle is improved from the structural side and the system side respectively.On the structural side,by adjusting the opening area of the air intake grille,the air intake flow rate of the heat exchanger is increased and the internal flow resistance is reduced.As a result,compared with the original vehicle,the allowable ambient temperature under the improved three operating conditions is increased by 2.14%,9.84%and 8.25%,respectively,and all of them have met the design goals with a certain margin.At this time,the wind resistance coefficient of the vehicle at high speed is 0.3638,which is 12.3 count lower than the original state.On the system side,the influence of compressor displacement and pump speed on vehicle thermal management performance is studied on the basis of the structural improvement scheme.The results show that increasing the compressor displacement can effectively improve the refrigeration performance of the air-conditioning system,but at the same time it will lead to the deterioration of the air-conditioning system’s economy and the engine cooling system’s heat dissipation performance.However,increasing the pump speed has little effect on improving the heat dissipation performance of the cooling system under low-speed climbing conditions.Therefore,after comprehensive consideration,it is recommended to replace the compressor with a larger displacement without adjusting the pump speed.By replacing the compressor with a displacement of 120 cm~3,the refrigeration performance of the air conditioning system can be improved on the premise that the allowable ambient temperature can meet the design target,so that passengers can drive in a comfortable environment,and finally the collaborative optimization of the thermal management and aerodynamic performance of the vehicle is realized. |
